Nozzles used in humidifier and nebulizer atomizers are often of the Venturi type. These Venturi nozzles usually have a small orifice through which a gas is forced to cause its expansion. The expanding gas jet is directed through, or over, a Venturi chamber containing a fluid whereby an effected vacuum draws droplets into the gas stream. This mixture is usually passed through a second or larger orifice permitting a secondary expansion during which droplet groupings tend to disassociate. The aerosol mixture may then be impinged upon a baffle to further reduce the size of droplets in suspension before being passed out of the device.
Three components, and their associated dimensions, are essential to the design of these nozzles. These components include a smaller or jet orifice, with its jet diameter; a larger or aerosal orifice, with its aerosol diameter; and a Venturi chamber, with its spacing between the jet and aerosol orifices. Additionally, it is critical that the centerline of the aerosol orifice be aligned with the centerline of the jet orifice in an assembled nozzle. Any deviation from specification greatly affects nozzle performance.
The manufacture of high quality, nebulization nozzles (those capable of producing a mist in the 1 to 10 micron size) therefore becomes quite costly with quality control expenses becoming a significant part of overall nozzle costs. These expenses have hampered the development of disposable nozzles.
A principal problem in making these nozzles out of materials acceptable for medical application, such as molded plastic materials, arises in the molding of the interior cavity. This cavity is usually formed with a long pin, used as the die, which is frequently about one-eight inch in diameter. The pin has a stepped-down portion which is used to form the jet orifice. This thin stepped-down portion is usually driven into the molding material intended to form the housing of the nozzle. The material is penetrated to its full depth, or alternatively, through its full depth and beyond. During this operation the pin often bends slightly and wears a side of the formed hole. Sometimes the pin breaks off in the hole. In many instances, therefore, an irregular hole results from the manufacturing process. Moreover, as a result of this process "molding flash" is often generated which extends into intended passageways. When the pin penetration is only to full depth, a "skin" is often left over the end of the molded hole. In addition, the thin stepped-down end of the pin has a tendency to move off of center during the molding process thus producing a misalignment of jet orifice to aerosol orifice in an assembled nozzle.
These molding process defects contribute to high rejection rates, increase mold costs, increase mold maintenance costs, and increase quality control costs.
What is desired, therefore, is a method of manufacturing these nozzles in which the enumerated problems and defects are eliminated or reduced so that the nozzle produced is economical enough to be disposable.
An object of this invention is to provide a method of manufacturing Venturi type nebulization nozzles wherein molding skin and flash defects are reduced.
Another object of this invention is to provide a method of manufacturing said nozzles wherein misalignment of orifices defects are reduced.
A further object of this invention is to provide an nebulization nozzle which is economically disposable.
Another object of this invention is to provide a disposable nozzle having a reduced number of parts.
Another object of this invention is to provide a disposable nozzle having essential functions defined at the interfaces of two mating parts.
An even further object of this invention is to provide a disposable nozzle wherein the essential functions defined at mating part interfaces are defined by mating part interfaces.